Abstract
The entirety of this particular review article demonstrates an in-depth analysis of the overall functionality of nutritional functional foods, imperative bioactive compounds, and essential biomarkers within the metabolic pathway and in chronic disease progression. Specifically, this review article assesses the efficacy of a plethora of functional foods and their associated bioactive compounds via the interpretation of epidemiological research studies that were conducted in the following design formats: cohort design, case-control design, cross-sectional design, and randomized controlled trial design. Although there has been a source of ambiguity demonstrated by food scientists and government organizations surrounding what would be the standard definition of functional food, this review article attempts to advocate for a contemporary definition that acknowledges the primary attributes of present-day functional food. Having said this, the main intention of this review article is to help address the necessity of analyzing the overarching efficacy of specific functional foods via the analysis of different retrospective epidemiological studies. Moreover, this review article will acknowledge which specific epidemiological study research design format is most applicable in the evaluation of functional food products within upcoming epidemiological studies. Ultimately, food scientists and nutritionists alike will get the opportunity to develop an all-encompassing contemporary definition for functional food upon the recognition and incorporation of different epidemiological study research design formats in a timely and cost-effective manner. KEYWORDS: Functional food, bioactive compounds, biomarkers, epidemiology, cohort design, case-control design, cross-sectional design, and randomized controlled trial design.